Moderna to begin clinical trials of Covid booster shots for variant from South Africa, sends to NIH for study

Moderna said Wednesday it has shipped to the National Institutes of Health doses of a new Covid-19 vaccine designed to provide better protection against the highly contagious coronavirus variant spreading in South Africa.

The vaccine – which Moderna is calling mRNA-1273.351 – is ready to be tested in an early-stage clinical trial to determine if it can be used as a booster shot against the South African strain, also known as B.1.351, the company said. Moderna has found its current two-dose regimen generates a weaker immune response against the strain from South Africa, though the company said antibodies in patients remain above levels that are expected to be protective against the virus.

“Moderna is committed to making as many updates to our vaccine as necessary until the pandemic is under control,” Moderna CEO Stephane Bancel said in a press release. “We hope to demonstrate that booster doses, if necessary, can be done at lower dose levels, which will allow us to provide many more doses to the global community in late 2021 and 2022 if necessary.”

U.S. health officials are growing concerned about new, emerging variants of the virus, particularly the B.1.351 strain, which has been shown to reduce the effectiveness of vaccines both on the market and under development. In recent weeks, White House Chief Medical Advisor Dr. Anthony Fauci has pushed Americans to get vaccinated as quickly as possible before potentially new and even more dangerous variants of the virus emerge.

As of Tuesday, the Centers for Disease Control and Prevention has identified 1,881 cases of the B.1.1.7 variant, first identified in the U.K. The U.S. agency said it has identified 46 cases of the B.1.351 strain, from South Africa, as well as five cases of P.1, a variant first identified in Brazil.  As more people become infected, the more likely it is that even more problematic mutations will arise, medical experts say.

On Monday, the Food and Drug Administration released updated guidance that said modified Covid-19 vaccines that work to protect against new, emerging variants may be authorized without the need for lengthy clinical trials. The FDA would clear the new vaccine as an amendment to a company’s originally approved emergency use application, thus accelerating the regulatory review process.

Moderna first announced on Jan. 25 that it was working on a booster shot to guard against the variant in South Africa.

The company said Wednesday that it plans to evaluate three approaches to boosting immunity. The first approach would use variant-specific booster shots, such as mRNA-1273.351, but at a lower dose than the original vaccine. The second approach would combine the original vaccine with a variant-specific vaccine into a single shot at 50 micrograms or lower, Moderna said. The third approach would test a third shot of the original vaccine at a lower dosage.

Moderna said it also plans to test the original vaccine and the new, booster shot as a two-dose regimen in people without coronavirus antibodies.

Separately, the company also announced that it expects to produce up to 1.4 billion Covid-19 vaccine doses in 2022. It also has raised its base-case global production estimate from 600 million doses to 700 million doses this year.

Moderna said the 1.4 billion doses in 2022 is with the assumption the vaccine will be administered as its current level of 100 micrograms. If the vaccine is found to be effective at a lower dosage level, the company could supply up to 2.8 billion doses in 2022, the company said.

Moderna has a deal with the U.S. government for 300 million doses. The company has shipped about 55 million doses to the U.S. so far. It expects to complete delivery of the first 100 million doses to the U.S. by the end of the first quarter 2021, the second 100 million doses by the end of May 2021 and the third 100 million doses by the end of July 2021.